Identification and functional characterization of NbMLP28, a novel MLP-like protein 28 enhancing Potato virus Y resistance in Nicotiana benthamiana.

Background: Major latex proteins (MLPs) belong to the MLP subfamily in Bet v 1 protein family and respond to both biotic and abiotic stresses, which play critical roles in plant disease resistance. As the type species of widely distributed and economically devastating Potyvirus, Potato virus Y (PVY) is one of the major constraints to important crop plants including tobacco (Nicotiana benthamiana) worldwide. Despite the great losses owing to PVY infection in tobacco, there is no previous study investigating the potential role of MLPs in developing resistance to viral infection.

Results: In this study, for the first time we have identified and functionally analyzed the MLP-like protein 28 from N. benthamiana, denoted as NbMLP28 and investigated its role in conferring resistance to N. benthamiana against PVY infection. NbMLP28 was localized to the plasmalemma and nucleus, with the highest level in the root. NbMLP28 gene was hypothesized to be triggered by PVY infection and was highly expressed in jasmonic acid (JA) signaling pathway. Further validation was achieved through silencing of NbMLP28 through virus-induced gene silencing (VIGS) that rendered N. benthamiana plants more vulnerable to PVY infection, contrary to overexpression that enhanced resistance.

Conclusions: Taken together, this is the first study describing the role of NbMLP28 in tobacco against PVY infection and provide a pivotal point towards obtaining pathogen-resistant tobacco varieties through constructing new candidate genes of MLP subfamily.